Oral endotracheal tubes are used by anesthetists to administer oxygen/anesthesia mixtures to a patient during a surgical procedure involving the throat, the larynx, or other similar locations which are normally reached by the surgeon through the mouth of the patient.
Endotracheal tubes have commonly been used for various types of surgery including ordinary surgical procedures and more recently surgical procedures using a laser surgical instrument for example a CO.sub.2 laser device. However, soon after the introduction of the laser to otolaryngology, a branch of medicine dealing with the throat, nose, and ears, reports of the combustion of the flammable material of endotracheal tubes during CO.sub.2 laser endoscopic surgery in the proximity to the airway began to appear. Subsequently, the combined flammabilty of the anesthetic/oxygen mixture coupled with the ability of the CO.sub.2 laser to ignite the material of the tube and initiate combustion which is greatly intensified by the highly flammable gases present have been resent, reported.
Various techniques and products have been utilized to address the problem including wrapping the tube with metallic foils. However, the use of a metalic foil wrapping introduces several problems including the fact that it is difficult to maintain the wrapping and simultaneously achieve desired flexibility of the tube. Additionally, metallic foil wrapping provides an another hazard by creating a reflective surface for the laser and reflection of the laser beam from the foil wrapped tube can cause unintentional damage to tissue surrounding the area being operated on, which is not anticipated by the procedure and/or operator (surgeon). Experimentation has been carried out with various inhaled gas mixture with the intention of mixtures preventing the ignition of the combustible anesthesic/oxygen mixture with little, or no, known success, as O.sub.2 in life supporting concentrations must always be present.
CO.sub.2 laser otolaryngological surgery offers significant advantages over prior surgical means but to date no method or apparatus is known which successfully eliminates or diminishes the possibility of fire and disaster occurring if the laser beam contacts and/or penetrates to the combustible material of the endotracheal tube during the procedure.
The endotracheal tube is constructed of highly flammable material usually PVC or rubber. When a laser beam contacts the tube even for a short period of time, a small area of the tube receives a high level of energy which can melt and/or ignite the tube material, and aided by oxygen concentrations usually near 100% inside the tube, results in a fire that is nearly impossible to extinguish with usually catastrophic results for the patient. Surgeons and anesthesiologists report a large number of near miss occurances (about 50%) where the tube was beginning to melt but had not yet flashed into a fire from laser contact.